Suggestions for a fair redistricting process (contains no partisan data)

September 16th, 2019, 9:41am by Sam Wang

Carolina legislators have an unusual task: they are instructed by the Superior Court to undo a partisan gerrymander, but they are not allowed to use partisan voting data. Here are some suggestions for carrying out this task successfully.

Don’t start with random maps. (In the case of North Carolina this ship already sailed. But it would be part of best practices in the future.) Natural geography works against treating the two parties equally. If you pick boundaries at random, requiring only that minimal criteria like population equality and compact shapes are met, you will generally end up with a Republican-leaning map.

It’s not just that urban areas vote Democratic. It’s that they do so monolithically – at higher percentages than rural areas vote Republican. In addition, there is a subtle point: city boundaries contain the vestiges of racial segregation. When a city has the option of incorporating an outlying region or not, race is often a factor in the decision. By using a city boundary, one is often also segregating by race.

The redistricting committees, which are controlled by Republicans, wanted to start with randomly generated maps. They had data on the properties of these plans. that such maps favored their own party on average. (see Plaintiff Exhibit 10 of N.C. Superior Court decision)

Seemingly neutral rules contain implicit judgments about what’s a good value to pursue – “algorithmic bias.” The use of a random selection of Chen’s maps implicitly says that compact shapes are more important than treating the major parties equally, or attending to the needs of specific communities.

However, some of the maps don’t have as much bias – so it is still possible to observe those rules, yet also look after communities. That requires human input.

Whatever maps you start with, take into account communities of interest. It is well known that neighborhoods and communities have shared interests. Redistricters have a responsibility to make sure those interests are looked after. And nothing in the court order prevents doing this.

It is said that “communities of interest” are a hard-to-define concept. This is true, but it doesn’t relieve the responsibility of redistricters to consider them! To read more about communities of interest, see the explainer we wrote in our Guide to Michigan Redistricting.

A randomly generated line can slice a community in two, just like an unwanted superhighway. It is important to prevent such lines from cutting communities up.

Lines can also throw together communities by chance. You wouldn’t put one pair of pants on your left leg, and another pair on your right leg!

To pick an example, Guilford and Randolph Counties are the site of Senate districts 26 and 27. At their boundary is High Point, an urban community that isn’t much like Randolph County. But some of it probably needs to be paired, because of contiguity requirements. The question is: which parts?

(Side note: the Court said voting district FEN1 in the far southeast of district 27 can’t be altered because it was added to the district by the special master. Otherwise, almost all of High Point could go in the 27th. Unless the Court decides otherwise, neighboring district 24 can’t be used to change district 27.)

Prevent inadvertent racial bias. Because ethnic-minority groups often vote differently from nearby ethnic-majority groups, representing them is tricky. Split the minority community up, and it has no chance at electing a representative. Pack it into a single district, and it loses the chance to have a say elsewhere. Treating a group fairly requires a careful balance.

You have to make a value judgment on the relative importance you assign to compactness, making sure groups gain at least some representation, and whether to maximize the number of seats that a particular group ends up getting.

Here are some simple rules of thumb.

Where there is racial polarization, a black population of 37-49% empowers representation. In expert testimony provided in the recent Virginia Bethune-Hill racial gerrymandering case, Prof. Moon Duchin showed that in districts that were able to elect Democratic representatives, a black population of 37% was always enough to elect a representative of their choice.

37% is not a fixed threshold – it depends a lot on the politics and priorities of neighboring communities. With recent trends of suburban and exurban politics, those communities sometimes align with communities of color and the threshold is lower. In extremely polarized regions, the threshold is higher. The amount of alignment affects the exact threshold for avoiding racial bias, whether purposeful or inadvertent.

Anyway, if the black population falls a little below this range, it may be worth scrutinizing the boundaries. And don’t send a boundary down the middle of a community to make two districts with far smaller fractions of black citizens.

Majority-black districts are no longer necessary for effective representation. In decades past, it was considered necessary to draw majority-black districts in order to guarantee representation. With recent trends in crossover voting, however, such majority-minority districts are no longer necessary for minorities to effectively participate in the political process.

Recently, majority-black districts were a telltale sign of a racial gerrymander in the federal Bethune-Hill case. In that case, 11 out of 12 districts were drawn to have a 55% black voting age population (BVAP), but it would have been possible to draw 15 black-opportunity districts. Because the legislators had used an excessively high BVAP quota, the map was redrawn.

In short, overpacking of black voters leads to lopsided wins that artificially reduce their opportunities to gain fair representation.

In some areas, drawing reasonable boundaries inevitably leads to majority-black districts. But the argument that such lines are necessary to comply with federal law goes against current constitutional interpretation if the focus on race plays an unconstitutionally large role in the line-drawing.

Finally, Blake Esselstyn has drawn nice maps of the regions to be redrawn. These show the districts in violation of state law: